What Is an Alcohol Interlock & How It Works | Smart Start

Do you need to get an alcohol interlock installed to get back on the road? No doubt you’ve got some questions about how an interlock works. Go no further! In this article, we’ll explain all you need to know about interlocks and how they work.

Smart Start Interlocks has been installing interlocks in New Zealand since 2013. Since then, we’ve gone from installing hundreds of interlocks per year to thousands, often as part of the alcohol interlock programme or part of the voluntary interlock device installation in NZ.

Smart Start’s interlocks use fuel cell technology, the same technology as Police breathalysers, meaning alcohol readings are reliable and accurate.

Interlocks are a similar size to a smartphone and are discreetly installed near the driver's seat to avoid drawing attention. They measure the alcohol level using an ethanol-specific fuel cell sensor - a sensor that reacts to any alcohol molecules your breath contains.

When using an interlock, there are two different measured alcohol tests to be aware of: the initial test and rolling retests.

Initial tests are the tests that must be taken before the vehicle will start. Once you turn your ignition on, the device will initialise and call for a test. Different interlock providers have different blowing techniques to ensure it is an ‘actual person’ blowing into the device, and not just a bag of air.

Smart Start’s interlocks provide a very easy (and sanitary) blow-hum. You blow into the personal breathalyser Smart Start device while saying the word ‘who’. Some providers require a blow and then a suck. We’ll let you decide which option you’d prefer.

Initial tests prove you have not got any alcohol in your system, and that you’re safe to drive. Once the initial test has been passed, you start your vehicle and begin your trip.

Rolling breath testing will occur randomly while you drive. These are to prove that you have not had anything to drink since starting your vehicle.

When the device calls for a rolling retest, you typically have five minutes to complete the test. If you’re not comfortable taking the test as you drive, this allows plenty of time to find a safe place to pull over.

In the event you fail or skip a rolling retest, the device will NOT turn off your vehicle. However, any failed or skipped tests are recorded and will likely lead to an extension of your interlock programme, so it’s very important you complete them all as required.

During a monthly service, the technician will check your interlock, perform any necessary updates, download the data, and perform a calibration to ensure the device is accurate.

Servicing takes approximately 15 minutes and can be done at any of our authorised interlock installer network.

Your interlock service is due every month on the same day as it was installed. You have a 7-day grace period on either side of that date; don’t leave it to the last minute. If you miss your monthly service, the device will lock out, and you won’t be able to start your vehicle.

Can you drink at all with an interlock device?

You can't drink or have alcohol in your system when attempting to drive with an interlock device - it doesn't matter that the legal limit of breath alcohol is 250mcg per litre of breath, you need to be alcohol-free.

After drinking alcohol, the only way to drive a vehicle that has an interlock device installed is when all of the alcohol and effects of alcohol have left the body. You will have to provide an alcohol-free breath sample to drive.

How long after you stop drinking can you pass an interlock device?

You need to wait at least 12 to 24 hours after the final drink - this is because the body processes one standard drink of alcohol per hour. At the same time, there's residual alcohol that can stay on the breath for longer than the lower end of this amount of time.

Plus, before menstruation, women may experience higher BACs (blood alcohol concentrations) because of hormonal factors, which affect the body's capability of processing alcohol.

How long does alcohol stay in your system?

This really depends on how your body processes alcohol and the test used, but in terms of the blood alcohol level or blood alcohol concentration (BAC), and the breath, the alcohol can remain in the system for 12 to 24 hours.

But for hair tests, alcohol can actually remain in the system for up to 90 days - and this is worth considering for separate prolonged consumption tracking cases.

Is it Time to Install an Alcohol Interlock Device on Your Vehicle?

Starting your interlock installation is very easy. Call us on 0800 002 182 (we’ll answer within 30 seconds) to set up a file. Provided you have the information required, we can have an interlock installed within a day, subject to our service centre's availability.

Our friendly call centre based in Maungaturoto is available from 7 am–5 pm from Monday to Friday. We have an emergency after-hours helpline if you require assistance outside business hours.

It’s our mission to make the interlock programme as quick and easy as possible, and we also have more information on the NZTA subsidy page, should you need support. We’d love to help. Contact our team to have your interlock device installed.